Foreign matter detection method of LC series topology wireless charging system

Abstract

The invention aims to provide a foreign matter detection method for an LC series topology wireless charging system. The method is relatively low in hardware cost, high in reliability and relatively high in precision. The method comprises the following steps that: step 1, in a primary power-on calibration stage, after power-on, the natural resonant frequency f, the quality factor Q and the equivalent direct current resistance of an LC network of a transmitting end are calculated, and recorded as common parameters; and 2, the output current If of a coupled current sensor is collected in real time, and the effective value Uf of the input voltage of an excitation source and the current working frequency f1 of the excitation source during sampling are recorded, the parameters are substituted into a quality factor change rate conversion formula, so that the change rate of the quality factor Q caused by the intervention of metal foreign matters is to calculated,if the change rate of the current quality factor Q is smaller than a set metal foreign matter detection judgment threshold value, an alarm is given, and charging is stopped, and if the change rate of the current quality factor Q is within the set foreign matter detection judgment threshold range, a charging system is safe, and charging is continued.

Description

technical field [0001] The invention relates to the technical field of wireless charging, in particular to a foreign object detection method of an LC series topology wireless charging system. Background technique [0002] Wireless charging foreign object detection technology has always been a technical hotspot in the industry's focused research. So far, the industry has proposed various foreign object detection methods, but most of the implementable methods focus on the connection stage of wireless charging. The detection of metal foreign objects in the process of wireless charging is deliberately ignored. The main reason for this phenomenon is that the application of wireless charging is still in its infancy, the application scene is fixed and single, and the charging height of the inductive wireless charging solution has great limitations. In order to adapt to the current application scenarios and make the power receiving equipment for inductive wireless charging work at t...

AI Technical Summary

Problems solved by technology

With the increase of the charging height of the inductive wireless charging system, a breakthrough has been made in the degree of freedom of placement, but it also brings another problem that needs to be solved urgently, that is, the detection of metal foreign objects in the wireless charging process.

At present, there are three main detection methods on the market: PowerLoss method, receiving device Q value communication method, and structural limitation method, but there are certain defects. For example, although the PowerLoss method is simple to implement and low in software and hardware costs, the detection accuracy of foreign objects is poor. , although the receiving device Q value communication method can accurately identify metal foreign objects, it has high requirements for hardware and poor compatibility of devices, while the structural limitation method has a single charging scene, large limitations of powered devices, poor reliability, and cannot be detected and identified Only passive defense, high risk

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